Walking mine roof support



July 4, 1967 w. WILKENLOH WALKING MINE ROOF SUPPORT 4 Sheets-Sheet 1 Filed June 30, 1964 Am HEZM Mara/10H KHEL BEHUER .7/1 yen/0m.

July 4, 1967 w. WILKENLOH WALKING MINE ROOF SUPPORT 4 Sheets-Sheet 5 Filed June 30, 1964 Fig. 0

v MA v July 4, 1967 w. WILKENLOH 3,328,967 WALKING MINE ROOF SUPPORT Fig. 8

J J6 ill/I5 J5 I i 37 4" 2-4" Jnren/ors. Mead/)7 4451a,, :04 a/' Braucr' United States Patent 27 Claims. (or. 61-45) The present invention relates to mine roof supports in general, and more particularly to an improved mobile or walking mine roof support for use in underground coal mines and the like. Still more particularly, the invention relates to a walking mine roof support which is suitable for use in underground mines having uneven roofs and/ or floors so that the floorand roof-engaging elements of the mine roof support must be free to move to a large number of different positions in orderto insure satisfactory propping of the mine roof and to thus avoid the possibility of cave-in with resultant danger to the safety of miners.

Mine roof supports of the general character to which the present invention pertains normally comprise one, two or more pairs of bit props which are provided with roof-engaging bars and floor-engaging sole plates, a connecting or supporting structure which carries the props, and a motor in the form of a cylinder or the like which causes the props to advance toward the mine face. As a rule, the motor comprises a horizontal cylinder whose piston rod is connected to the customary material-removing conveyor and which causes the conveyor to advance toward the mine face when the props are disengaged from the mine roof. The conveyor extends along the mine face to collect and to remove material which is being mined, for example, coal or the like. When the conveyor has been advanced by a step and the piston rod is to be retracted in the cylinder, the props are shortened in the customary way so that their roof-engaging bars are moved to a level below the mine roof, whereupon the apparatus is free to advance by a step toward the mine face.

It is an important object-of the present invention to provide a very simple, compact, easy-to-handle and very rugged walking mine roof support which may be used in underground coal mines and other types of excavations, and wherein the props and their fioorand roofengaging elements are movable with reference to each other to an extent necessary to avoid jamming and to insure that such elements may be moved in large surfaceto-surface contact with the mine roof and/ or mine floor.

Another object of the invention is to provide a walking mine roof support of the just outlined characteristics wherein the props, the roof-engaging elements and the floor-engaging elements are constructed and assembled in such a way that at least some thereof automatically return to optimum starting positions as soon as they become disengaged from the walls surrounding an underground excavation.

A further object of the invention is to provide a walking mine roof support wherein the roof-engaging bars and the floor-engaging sole plates are constructed and mounted in such a way that each thereof is free to yield in response to engagement with mine roofs and/or mine floors which exhibit very large recesses, protuberances and other unevennesses such as could cause damage to or breakage of parts which are not free to yield by swivelling, tilting, rocking, turning, shifting or other movement with reference to the adjacent parts of the mine roof or mine floor.

Duisburg-Wanheim,

An additional object of the invention is to provide a walking mine roof support of the just outlined characteristics which may be readily and rapidly converted into one having two, three or even a higher number of pairwise arranged props.

A concomitant object of the instant invention is to provide a walking mine roof support wherein a damaged or deformed part may be readily and rapidly exchanged without necessitating complete dismantling of the entire apparatus, wherein the props are free to move with reference to each other (i.e., from a substantially vertical position) to an extent which is just sufficient to avoid damage to the apparatus, and wherein the props are always held against excessive oscillatory movement such as could impede rapid progress of the mine roof support along the mine floor and proper reengagement of bars with the mine roof.

A further object of our invention is to provide a walking mine roof support wherein the height of the floorengaging elements is rather negligible so that the center of gravity of such elements is close to the mine floor to insure great stability of the apparatus and to avoid any danger of overturning when the mine roof support is in actual use.

Another object of the invention is to provide improved connections between the main supporting structure and the props of a walking mine roof support.

An ancillary object of the invention is to provide a novel sole plate construction for a walking mine roof support of the above outlined characteristics.

With the above objects in view, one feature of the present invention resides in the provision of a walking mine roof support which comprises an elongated rigid supporting member preferably consisting of hollow profiled stock (such as a U-beam or the like), a pair of leading extensible and contractible pit props and a pair of trailing extensible and contractible pit props arranged in such a way that the props of each pair are disposed at the opposite sides of the supporting member, coupling means articulately connecting one pair of props with the supporting member, and a connector resembling a scale beam and serving to articulately connect the other pair of props with the supporting member. This connector comprises a median portion which is rotatable on or is otherwise fulcrumed on the supporting member, and two end portions each of which is articulately connected with one prop of the corresponding pair of props by pivots, hinges, ball and socket joints or the like.

In accordance with one preferred embodiment of our invention, the connector may be a rigid sole plate which is connected 'to the lower end portions of the corresponding props. Alternatively, the connector may be connected with the corresponding props at a level above the sole plates and may support a two-armed carrier whose arms are coupled to the props so that the props are connected to the supporting member at two spaced points, namely, through the intermediary of the connector and through the intermediary of the carrier,

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved mine roof support itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a side elevational view of a walking mine roof support which comprises four pit props and is constructed in accordance with a first embodiment of the present invention;

FIG. 2 is a fragmentary top plan view of the mine roof support with the pit props omitted;

FIG. 3 is a fragmentary front elevational view of the mine roof support, as seen from the left-hand side of FIG. 1, with portions of the leading sole plate broken away;

FIG. 4 is a fragmentary rear elevational view of the mine roof support, as seen from the right-hand side of FIG. 1, with the trailing sole plate shown in transverse vertical section;

FIG. 5 is a fragmentary side elevational view of a second walking mine roof support wherein each trailing pit prop carries a separate sole plate;

FIG. 6 is a fragmentary transverse vertical section as seen in the direction of arrows from the line VIV1 of FIG. 5;

FIG. 7 is a side elevational view of a third walking mine roof support which comprises three pairs of pit props; and

FIG. 8 is a transverse vertical section as seen in the direction of arrows from the line VIIIVIII of FIG. 7.

Referring to FIG. 1, there is shown a mobile or walking mine roof support which is constructed in accordance with a first embodiment of the present invention. The support comprises four extensible and contractible pit props including two leading props 1 and two trailing props 1a. As shown in FIG. 2, each leading prop 1 is aligned with one of the trailing props 1a, and the four props are disposed at the corners of a rectangle. Each prop comprises a lower tubular portion or cylinder and an upper tubular portion or plunger which is telescoped into the respective cylinder. The exact construction of the hydraulic circuit which controls the admission and evacuation of oil or another pressure medium into and from the props forms no part of the present invention. It sufiices to say here that the props are caused to extend when they should support the mine roof and are caused to contract when the mine roof support is to advance toward the mine face. During walking (i.e., when the mine roof support is advanced toward the mine face), the sole plates 5 and 5' at the lower ends of the props 1 and 1a shuffle along the mine floor and the roofengaging cap at the upper ends of the props is disengaged from the mine roof.

The roof-engaging cap comprises two pairs of elongated plate-like roof engaging members 2, 2' called roof bars,

each of which is connected with the upper end portion I of a prop. In the illustrated embodiment, the connection between each roof bar and the upper end portion of the respective prop comprises a universal joint including a ball 1A at the upper end of the prop and a complementary socket 2a on the respective roof bar. Such universal joints enable the roof bars 2 and 2 to follow the outline of an uneven mine roof and to insure that the area of contact between the mine roof and the roof-engaging cap is comparatively large. The trailing end portion of each leading roof bar 2 is connected with the leading end portion of the corresponding trailing roof bar 2' by a coupling which allows the roof bars to be tilted with reference to and to be moved toward and away from each other. As shown in FIG. 1, the adjacent end portions of aligned roof bars 2, 2 are provided with downwardly extending flanges 2d having vertical slots 2e for a bolt 2b which cooperates with a nut and is biased by a spring 2c which tends to maintain the roof bars 2, 2 in a common plane by biasing the flanges 2d into face-to-face abutment with each other. The arrow C in FIG. 1 indicates the direction of forward movement of the mine roof support, i.e., the mine face is located to the left of FIG. 1.

The mine roof support further comprises an elongated rigid supporting member or assembly member 3 which is spaced from the mine floor and extends between the pairs of leading and trailing props 1, 1a. This supporting member is a U-bar having a very high moment of resistance and is articulately coupled with the props in a manner best shown in FIGS. -3 and 4. It can be said that the supporting member 3 is the stifi backbone of the mine roof support. Referring first to FIG. 3, the lower tubular portions of the leading props 1 are received in and may be integral with short vertical cups 4 which are coupled to the leading sole plate 5 by a pair of ball and socket joints. Each of these joints comprises a ball 6 provided at the upper side of the leading sole plate 5 and a complementary socket at the lower end of the respective cup 4. The joints further comprise suitable pins or the like which insure that each ball 6 remains in but may rotate with reference to the corresponding socket. Each cup 4 is provided with a laterally extending bifurcated por-tion or lug 7 which is coupled to lugs 8 on the supporting member 3 by means of horizontal pivots 9. Thus, the leading sole plate 5 may be tilted about a transverse horizontal axis which is perpendicular to the axes of the leading props 1, and the pivots 9 insure that the leading props (and more particularly the cups 4 which receive the lower tubular portions of the leading props) may pivot about two spaced horizontal axes which are parallel with the longitudinal extension of the supporting member 3.

The web of the supporting member 3 supports the web of an elastically deformable two-armed carrier 11 which is secured thereto by bolts 10. A layer of elastic cushioning material 13 is interposed between the webs of the supporting member 3 and carrier 11 so that the latter has some freedom of movement with respect to the member 3. The upwardly extending flanges or arms 11a of the carrier 11 are connected with two ring-shaped guides 12 each of which surrounds the lower tubular portion of a leading prop 1. The connections between the arms 11a and guides 12 comprise horizontal bolts 10 and additional cushions 13 so that the guides may be tilted with reference to the carrier 11 to insure that each leading prop 1 is free to perform at least some movements with reference to the supporting member 3 such as are necessary to guarantee satisfactory engagement of sole plates and roof bars with the mine floor and mine roof, particularly when the mine roof and/ or the mine floor is full of protuberances so that the soleplates and the roof bars must be free to move to various positions of inclination with reference to a truly horizontal plane. The arms 11a of the carrier 11 and the cushions 13 between the arms 11a and guides 12 enable the leading props 1 to move toward and away from each other (see the double-headed arrow A in FIG. 3). The cushions 13 also allow for some tilting of the leading props 1 in directions indicated in FIG. 1 by a doubleheaded arrow B; i.e., it can be said that each leading prop may swivel to a limited extent but that each thereof will automatically return to a normal vertical or nearly vertical position when the bars 2 and 2 disengage from the mine roof.

As shown in FIG. 3, the supporting member 3 encloses a space to accommodate a double-acting hydraulic cylinder 14 which serves as a means for advancing or walking the mine roof support toward the mine face (arrow C). As a rule, the connection between the supporting member 3 and the cylinder 14 comprises a Cardanic joint. The supporting member protects the cylinder 14 against falling rock, moisture, and/or, dust. The overall dimensions of the member 3 are comparatively small so that the improved support is a rather compact and lightweight apparatus. It is to be mentioned here that the one-piece leading sole plate 5 may be replaced by two independent or interconnected sole plates each of which is then secured to the lower tubular portion of a leading prop 1.

While the lower tubular portions of the props 1 are rigidly secured to the respective guides 12, the connection between the trailing props. 1a and the supporting member 3 is constructed in such a way that the lower tubular portion of each trailing prop is reciprocable up and down.

. As shown in FIG. 4, the supporting member 3 comprises two laterally extending forked lugs which guide the rear cups 4' in such a way that these cups may move up and down. The trailing sole plate 5' comprises a centrally located ball 16 which extends into a complementary socket provided'on a yoke 17 which is secured to the flanges of the supporting member 3, and which may constitute an integral part of the supporting member. Additional ball and socket joints 18 are provided to connect the end portions of the trailing sole plate 5' with the cups 4 for the trailing props 1a.

The web of the supporting member 3 supports a second U-shaped carrier 19 which corresponds to the carrier 11 and whose upwardly. extending flanges or arms are connected with two ring-shaped guides 20, one for each of the trailing props 1a. The lower tubular portion of each prop 1a is reciprocable in the corresponding guide 20, and the articulate connections between the carrier 19 and parts 3, 20, 20 are constructed in the same way as described in connection with FIG. 3, i.e., there are elastic cushions 13 and bolts 10 which allow for some tilting of the carrier 19 with reference to the supporting member 3 and for some tilting of the guides 20 with reference to the arms of the carrier 19 which latter is elastic to further enhance the movability of trailing props 1a with reference to the supporting member.

The trailing sole plate 5' resembles a scale beam and constitutes a tiltable connector whose median portion is fulcrumed at 16 and whose end portions are a-rticul'ately connected with the trailing cups 4. Therefore, the trailing sole plate 5' may be tilted about a first horizontal axis which is parallel with the longitudinal extension of the supporting member 3 and about a second horizontal axis which is perpendicular to the longitudinal extension of the supporting member. This is indicated by dotted lines in FIGS. 1 and 4 of the drawings. When the trailing sole plate 5' is tilted in a manner as shown in FIG. 4, one of the props 1a moves up and the other prop 1a moves down by simultaneous elastic deformation of the carrier 19 so that each trailing prop assumes a position in which its axis is somewhat inclined with reference to the vertical.

The piston rod of the cylinder 14 may move forwardly to engage a customary conveyor which extends in front of the mine roof support (at right angles to the plane of FIG. 1) and is adjacent to the mine face so that the material which is being removed from the mine face may accumulate on and is automatically removed by this conveyor. When the piston rod of the cylinder 14 performs a forward stroke, the bars 2 and 2' engage the mine roof so that the mine roof support remains stationary but the conveyor is caused to advance by a step so as to move nearer to the mine face. In the next step, the props 1, 1a are caused to contract and the piston rod is retracted into the cylinder 14 whereby the sole plates 5 and 5' slide along the mine floor and the entire mine roof support moves nearer 'to the mine'face (arrow C in FIG. 1). Such manner of walking the mine roof support and the conveyor is well known in the art and, therefore, the conveyor has not been shown in the drawings. a

It will be noted that the upper sides of the sole plates 5 and 5' are practically free of any protruding parts which would .be likely to retain pieces of falling rock or the like. This is important because such falling debris could cause jamming of the mine roof support. Also, the articulate connections between the supporting member 3, the props 1, 1a and sole plates 5, 5 are just sufiicient to allow for tilting of such parts with reference to the member 3 but will not allow excessive tilting such as could result in excessive swinging of props when the mine roof support advances toward the mine face. Excessive tilting is undesirable because the props should rapidly return to substantially vertical positions in which they are ready to move the roof bars 2-, 2' back in supporting engagement with the mine roof. In other words, swinging or tilting 6 of the props from a vertical or nearly vertical position should be kept to a permissible minimum.

The underside of the trailing sole plate 5' (which is mounted not unlike a scale beam) may follow closely the outline of an uneven mine floor when the mine roof support is caused to advance toward the mine face. In addition, such mounting of the sole plate 5' insures that the mine roof support remains in the required position, i.e., that the mine roof support does not change the direction of its advance while walking on uneven terrain, because the comparatively stiff mounting of the leading sole plate 5 prevents excessive angular displacements of the trailing portion of the support. The rigid supporting member 3 also contributes to retention of the mine roof support in desired position with reference to the mine face.

The mine roof support of FIGS. 5 and 6 differentiates from the one shown in FIGS. 1 to 4 mainly in that the trailing sole plate construction comprises two separate plates 29a, and in a modified connection between the supporting member 3 and the trailing props 1a. This connection comprises a connector 21 resembling a scale beam which is rotatable on the rear portion of the supporting member 3. As viewed in FIG. 6, the connector 21 may be turned in a clockwise or counterclockwise direction and is provided with two pairs of laterally extending bifurcated arms or lugs 22 which receive horizontal pivots 23 fastened to the trailing cups 4'. Vertical retaining pins 25 insure that the pivots 23 remain in the slots 24 of the respective lugs 22.

Ring-shaped guides 26 for the lower tubular portions of the trailing props 1a are coupled to the arms of an elastic carrier 27 which is fixed to the connector 21 by bolts 28. Elastic cushions 13 insure that the guides 26 may be tilted with reference to the arms of the carrier 27, and a further cushion 29 is provided in the connection between the carrier and the top wall portion of the connector 21. The median portion of this connector resembles a flattened tube whereby the supporting member 3 automatically determines the extent to which the connector may rotate thereabout. The trailing props 1a are fixed to the guides 26.

If desired, the carrier 27 may be rigidly fixed to the supporting member 3, i.e., in front or rearwardly of the connector 21. In such mine roof supports, the trailing props 1a must be free to move vertically with reference to the guides 26. The connections between the trailing sole plates 29a and the lower tubular portions of the trailing props 1a are constructed in the same way as described in connection with the sole plates 5'. The direction in which the mine roof support is advanced toward the mine face is indicated in FIG. 5 by the arrow C and the construction of the roof bars 2, 2' is the same as described in connection with FIG. 1.

FIG. 7 illustrates a mine roof support with three pairs of props including a pair of-leading props 1, a pair of trailing props 1b, and a pair of intermediate props 1a. The articulate connection between the roof bars 2 of the intermediate props 1a and the common roof bar 2] of the trailing props 1b comprises forwardly extending lugs 30 which are welded to the roof bar 2} and horizontal pins 31 which are inserted in the roof bars 2'. The common sole plate 5' of the intermediate props 1a is articulately connected with the common sole plate 33 of the trailing props 1b by links 32 and horizontal pins 34 so that the sole plates 5 and 33 are movable with reference to each other in a manner indicated by broken lines. The connections between the sole plate 33 and the lower tubular portions of the props 1b comprise ball and socket joints to insure that the sole plate 33 may follow the outline of an uneven mine floor. The connection between the props 1b comprises a U-shaped elastic carrier 35 whose arms extend through eyes 36 provided on the lower tubular portions of the props 1b. The web of the carrier 35 comprises laterally extending plates which are traversed by horizontal pivots 38 extending through lugs 37 provided on the cups 4 for the lower ends of the props 1b. When the sole plate 33 is moved to the dotted-line position of FIG. 8, the carrier 35 is deformed and tends to return the props 1b to the full-line positions of FIG. 8. It goes without saying that the sole plate 33 may be replaced by two independent sole plates such as the sole plates 29a of FIGS. and 6.

The construction of the supporting member 3 and of its connections with the props 1 and 1a is the same as described in connection with FIGS. 1 to 4. Thus, the sole difference between the mine roof supports of FIGS. 1 to 4 and 7 to 8 is that the latter comprises an additional pair of props 1b which are articulately secured to each other, to the trailing sole plate 5, and to the trailing roof bars 2'. The trailing sole plate 5' constitutes a connector between the supporting member 3 and the props 1a, and it will be noted that this sole plate resembles a scale beam.

As shown in each of FIGS. 1 to 8, the connector which resembles a scale beam is preferably connected with the trailing props and/ or with the intermediate props. Thus, the mobility of trailing or intermediate props will normally exceed the mobility of leading props. Such construction of the mine roof support does not prevent it from moving into a sufficiently large surface-to-surface contact with the mine roof and/or mine fioor because the sole plates of the leading props normally advance along a portion of the mine floor which is comparatively smooth, whereas the sole plates of trailing and intermediate props often advance along a portion of the mine floor whose unevennesses are much more pronounced. This will be readily understood by considering that, during intervals between consecutive advances of the mine roof support, the material of the filling is likely to drop onto the mine floor to present additional obstacles against forward movement of the trailing sole plates. In other words, while the leading sole plates normally advance along a freshly formed and reasonably clean portion of the mine floor, the trailing sole plates must advance along a portion of the mine floor which, as a rule, is not as smooth and as clean as it was during advance of the leading sole plates.

Furthermore, the operators in charge of the mine roof support are in a position to observe the mine floor in front of the leading sole plates, whereas at least some portions of the mine floor just ahead of the trailing and/or intermediate sole plates are partially or fully concealed by the elements of the mine roof support. Therefore, the operators may remove any large pieces of rock or ore which are found in the path of the leading sole plates, and the operators are in a position to fill any depressions which might be present in the mine floor in front of the leading sole plates.

It goes without saying that two or more mine roof supports of the type shown in FIGS. 1 to 8 may be coupled to each other to form a single file of consecutively arranged supports and/ or that two or more such mine roof supports may be connected to form a row of supports which is parallel with the mine face.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member; coupling means securing the props of one of said pairs to said supporting member; a connector comprising a median portion tiltably mounted on said supporting member; and connecting means securing the end portions of said connector with the props of the other of said pairs.

2. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; coupling means securing the props of one of said pairs to said supporting member; a sole plate located below said supporting member and the lower end portions of the other of said pairs of props and comprising a median portion tiltably mounted on said supporting member; and connecting means securing the end portions of said sole plate with the lower end portions of props forming said other of said pairs.

3. A structure as set forth in claim 2, further comprising a ball and socket joint connecting the median portion of said sole plate with said supporting member.

4. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member; coupling means securing the props of one of said pairs to said supporting member; a connector comprising a median portion tiltably mounted on said supporting member; and joints tiltably coupling the end portions of said connector with the props of the other of said pairs.

5. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member; coupling means securing the props of one of said pairs to said supporting member; a connector comprising a median portion tiltably mounted on said supporting member; connecting means securing the end portions of said connector with the props of the other of said pairs; carrier means mounted on said supporting member; and guide means secured to said carrier means for guiding the props of said other pair for vertical reciprocatory movement with reference thereto.

6. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each thereof comprising a lower portion; coupling means providing articulate connections between the props of one of said pairs and said supporting member; a connector comprising a median portion tiltably mounted on said supporting member; joints tiltably coupling the end portions of said connector with the props of the other of said pairs; and guide means provided on said supporting member for guiding the lower portions of the props forming said other pair, said guide means including forked members in which said props of said other pair are movable vertically.

7. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each thereof comprising a lower portion; a connector comprising a median portion tiltably mounted on said supporting member; joints articulately coupling the end portions of said connector with the props of the other of said pairs; a pair of elastic carriers mounted on said supporting member, one for each pair of props and each comprising a pair of arms; and guides provided on the lower portions of said props, each guide being coupled to one arm of the respective carrier.

8. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member; coupling means securing the props of one of said pairs to said supporting member; a connector comprising a median portion turnably mounted on said supporting member; and connecting means securing the end portions of said connector with the props of the other of said pairs.

9. A structure as set forth in claim 8, wherein each of said props comprises a lower end portion and further comprising sole plates tiltably secured to the lower end portions of the props forming said other pair.

10. In a walking mine root support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member; coupling means providing elastically deformable tiltable connections between the props of one of said pairs and said supporting member; a single connector comprising a median portion tiltably mounted on said supporting member; and connecting means securing the end portions of said connector with the props of the other of said pairs.

11. A structure as set forth in claim 10, wherein said connector is secured to said trailing props.

12. A structure as set forth in claim 10, wherein each of said props comprises a lower end portion and further comprising a sole plate tiltably coupled to the lower end portions of props forming said one pair of props.

13. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member; first coupling means securing the props of one of said pairs to said supporting member; a connector comprising a median portion tiltably mounted on said supporting member; connecting means securing the end portions of said connector with the props of the other of said pairs; a third pair of props second disposed rearwardly of said trailing props; coupling means tiltably securing said third pair of props to said trailing props; and third coupling means tiltably securing the props of said third pair to each other.

14. A structure as set forth in claim 13, wherein each of said props comprises a lower end portion and further comprising a sole plate tiltably connected with the lower end portions of said third pair of props.

15. A structure as set forth in claim 13, wherein said third coupling means between the props of said third pair comprises a U-shaped elastic carrier having two arms each connected to one prop of said third pair.

16. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each comprising an upper end portion and a lower end portion; a pair of carriers secured to said supporting member, one for each pair of props and each comprising a pair of elastic arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carrier; roof-engaging elements tiltably secured to each other and to the upper end portions of said props; leading sole plate means tiltably secured to the lower end portions of said leading props; and trailing sole plate means tiltably secured to the lower end portions of said trailing props, at least one of said sole plate means having a median portion tiltably secured to said supporting member.

17. In a walking mine roof support, in combination, an

elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a plurality of carriers secured to said supporting member, one for each pair of props each of said carriers including a pair of arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carrier; a connector extending transversely of said supporting member and tiltably connected with the lower end portions of one pair of said props; and a,

tiltable connection between said connector and said supporting member.

18. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a plurality of carriers secured to said supporting member, one for each pair of props, each of said carriers including a pair of arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carrier; a transversely extending sole plate disposed beneath said supporting member and tiltably connected with the lower end portions of one pair of said props; and a tiltable connection provided between said sole plate and said supporting member and arranged to permit tilting of said sole plate about axes which are parallel with and perpendicular to the longitudinal extension of said supporting member.

19. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a plurality of carriers secured to said supporting member, one for each pair of props, each of said carriers including a pair of arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carrier; a sole plate extending transversely of said supporting member and tiltably connected with the lower end portions of one pair of said props; and a ball and socket joint connecting said sole plate with said supporting member.

20. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a plurality of carriers secured to said supporting member, one for each pair of props, each of said carriers including a pair of arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carrier; and a transversely extending connector rotatably mounted on said supporting member and tiltably connected with the lower end portions of one pair of said props.

21. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a plurality of carriers secured to said supporting member, one for each pair of props, each of said carriers comprising a pair of arms; a guide provided on each of said props, each of said guides being secure-d to one arm of the respective carrier; a transversely extending connector turnably mounted on said supporting member and tiltably connected with one pair of said props; a separate sole plate for each prop of said one pair; and ball and socket joints tiltably connecting said sole plate with the lower end portions of the respective props.

22. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a plurality of carriers tiltably secured to said supporting member, one for each pair of said props, each of said carriers including a pair of arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carrier; a single transversely extending connector having a. median portion tiltably secured to said supporting member; and pivot means securing the end portions of said connector to the lower end portions of one pair of said props.

23. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a pair of carriers secured to said supporting member, one for each pair of props, each of said carriers including a pair of. arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carriers; a transversely extending sole plate disposed beneath said supporting member; and joints tiltably connecting said sole plate with the lower end portions of one pair of said props and with said supporting member.

24. In a Walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower end portion; a plurality of carriers secured to said supporting member, one for each pair of props, each of said carriers including a pair of arms; a guide provided on each of said props, each of said guides being secured to one arm of the respective carrier; a pair of transversely extending sole plates disposed beneath said supporting member; joints tiltably connecting the lower end portions of each pair of props to one of said sole plates; and a further joint tiltably connecting one of said sole plates with said supporting member.

25. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of intermediate pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising an upper end portion and a lower end portion; a plurality of carriers, one for each pair of props, each of said carriers including a pair of arms; connecting means securing the carriers for said leading and intermediate props to said supporting member; a guide provided on each of said props; connecting means securing each of said guides to one arm of the respective carrier; roof-engaging elements provided on the upper end portions of said props; connecting means tiltably securing the roof-engaging elements of said intermediate props with the roof-engaging elements of said trailing props; sole plate means tiltably secured to the lower end portions of said props; and connecting means tiltably securing the sole plate means of said intermediate props with the sole plate means of said trailing props and with said supporting member.

26. In a walking mine roof support, in combination, anelongated rigid supporting member; a pair of extensible and contractible leading pit props; a pair of extensible and contractible trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member and each prop comprising a lower tubular portion and an upper tubular portion telescoped into said lower tubular portion; a connector tiltably secured to one pair of said props and to said supporting member; a carrier for each pair of props, each of said carriers including a pair of arms; connecting means including elastic cushions securing said carriers to said supporting member; ring-shaped guides provided on said lower tubular portions, at least one pair of said props being reciprocable in the respective guides; and coupling means tiltably connecting each of said guides with one arm of the respective carrier.

27. In a walking mine roof support, in combination, an elongated rigid supporting member; a pair of leading pit props; a pair of trailing pit props, the props of each pair being disposed at the opposite sides of said supporting member; sole plate means for each pair of props located beneath said supporting member and the lower ends of said props so as to support the latter at their lower ends; coupling means securing the props of one of said pairs of props to said supporting members; means connecting the sole plate means of the other pair of props to said supporting member tiltable about an axis located between said other pair and extending in direction of the elongation of said supporting member; and means connecting the props of said other pair to said supporting member movable in direction of the longitudinal axes of said props and substantially immovable in direction of the elongation of said supporting member.

References Cited UNITED STATES PATENTS 3,201,943 8/1965 Wilkenloh et al 61--45.2 3,218,812 11/1965 Wilkenloh 6145 FOREIGN PATENTS 1,310,723 10/1962 France. 1,361,408 4/1964 France.

DAVID J. WILLIAMOWSKY, Primary Examiner.

JACOB SHAPIRO, Examiner. 

1. IN A WALKING MINE ROOF SUPPORT, IN COMBINATION, AN ELONGATED RIGID SUPPORTING MEMBER ; A PAIR OF LEADING PIT PROPS; A PAIR OF TRAILING PIT PROPS, THE PROPS OF EACH PAIR BEING DISPOSED AT THE OPPOSITE SIDES OF SAID SUPPORTING MEMBER; COUPLING MEANS SECURING THE PROPS OF ONE OF SAID PAIRS TO SAID SUPPORTING MEMBER; A CONNECTOR COMPRISING A MEDIAN PORTION TILTABLY MOUNTED ON SAID SUPPORTING MEMBER; AND CONNECTING MEANS SECURING THE END PORTIONS OF SAID CONNECTOR WITH THE PROPS OF THE OTHER OF SAID PAIRS. 